He has....in Italy. Euro patent is pending. USA is applied for. Unfortunately, the US Patent Office puts "cold fusion" in the same category as "perpetual motion" and automatically rejects. Part of the reason for all the demos is to convince the various patent granting agencies to get off their duffs and "get it done".
The patent application says the source of energy is beta decay. Hasn't Rossi said since then that beta decay isn't involved?